DOE OSTI2020
Ca2Co2O5 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. there are four inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.31–2.86 Å. In the second Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.32–2.87 Å. In the third Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.32–2.92 Å. In the fourth Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.31–2.91 Å. There are seven inequivalent Co3+ sites. In the first Co3+ site, Co3+ is bonded to four O2- atoms to form CoO4 tetrahedra that share corners with two equivalent CoO6 octahedra and corners with two equivalent CoO4 tetrahedra. The corner-sharing octahedral tilt angles are 35°. There are a spread of Co–O bond distances ranging from 1.82–1.97 Å. In the second Co3+ site, Co3+ is bonded to four O2- atoms to form CoO4 tetrahedra that share corners with two equivalent CoO6 octahedra and corners with two equivalent CoO4 tetrahedra. The corner-sharing octahedral tilt angles are 35°. There are a spread of Co–O bond distances ranging from 1.82–1.96 Å. In the third Co3+ site, Co3+ is bonded to four O2- atoms to form CoO4 tetrahedra that share corners with two equivalent CoO6 octahedra and corners with two equivalent CoO4 tetrahedra. The corner-sharing octahedral tilt angles are 36°. There are a spread of Co–O bond distances ranging from 1.80–1.99 Å. In the fourth Co3+ site, Co3+ is bonded to four O2- atoms to form CoO4 tetrahedra that share corners with two equivalent CoO6 octahedra and corners with two equivalent CoO4 tetrahedra. The corner-sharing octahedral tilt angles are 36°. There are a spread of Co–O bond distances ranging from 1.82–1.97 Å. In the fifth Co3+ site, Co3+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with four equivalent CoO6 octahedra and corners with two equivalent CoO4 tetrahedra. The corner-sharing octahedra tilt angles range from 9–14°. There are a spread of Co–O bond distances ranging from 1.84–2.17 Å. In the sixth Co3+ site, Co3+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with four equivalent CoO6 octahedra and corners with two equivalent CoO4 tetrahedra. The corner-sharing octahedra tilt angles range from 10–14°. There are a spread of Co–O bond distances ranging from 1.93–2.18 Å. In the seventh Co3+ site, Co3+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with four CoO6 octahedra and corners with two CoO4 tetrahedra. The corner-sharing octahedra tilt angles range from 9–14°. There are a spread of Co–O bond distances ranging from 1.84–2.16 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Ca2+ and two Co3+ atoms to form corner-sharing OCa2Co2 tetrahedra. In the second O2- site, O2- is bonded to two equivalent Ca2+ and two Co3+ atoms to form corner-sharing OCa2Co2 tetrahedra. In the third O2- site, O2- is bonded to two equivalent Ca2+ and two Co3+ atoms to form distorted corner-sharing OCa2Co2 tetrahedra. In the fourth O2- site, O2- is bonded to two equivalent Ca2+ and two Co3+ atoms to form distorted corner-sharing OCa2Co2 tetrahedra. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and two Co3+ atoms. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and two Co3+ atoms. In the seventh O2- site, O2- is bonded in a 5-coordinate geometry to three Ca2+ and two Co3+ atoms. In the eighth O2- site, O2- is bonded in a 5-coordinate geometry to three Ca2+ and two Co3+ atoms. In the ninth O2- site, O2- is bonded in a 6-coordinate geometry to four Ca2+ and two Co3+ atoms. In the tenth O2- site, O2- is bonded in a 6-coordinate geometry to four Ca2+ and two Co3+ atoms. In the eleventh O2- site, O2- is bonded in a 6-coordinate geometry to four Ca2+ and two Co3+ atoms. In the twelfth O2- site, O2- is bonded in a 6-coordinate geometry to four Ca2+ and two Co3+ atoms.